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AJvYcCUE9kwKiN+EmLfqXcv6qYwqcOErwoLw4+xhhFgCTIrBAPxOVjjvn8DPXjb4uHtz591T04OHEvv77QTIjQYHSYsM6cyysA6cdxdtQQ== X-Gm-Message-State: AOJu0YzRqzC51INMWzrUvqljWS4rx/IWbC7JU1ILPEhwou1qwnmxH0xC Lw5hAjba4pTxmXgQ4dRVKZ7uhDeuWSjlpDBfyFDOqWWRkS8VTn2dvNoKm/crfb1hhVzCndlva19 r3Q== X-Google-Smtp-Source: AGHT+IGomtDJcb51lvQMFTT5YaGoxW/vZTzkUSuhiTLoa8vZxcxiKEVXH4dmB1G1pZ9i7NSp+ryn6A1areA= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:ad8d:0:b0:dc6:e5d3:5f03 with SMTP id z13-20020a25ad8d000000b00dc6e5d35f03mr543024ybi.4.1713535088599; Fri, 19 Apr 2024 06:58:08 -0700 (PDT) Date: Fri, 19 Apr 2024 06:58:06 -0700 In-Reply-To: <20240419112432.GB2972@willie-the-truck> Precedence: bulk X-Mailing-List: linux-mips@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240405115815.3226315-1-pbonzini@redhat.com> <20240405115815.3226315-2-pbonzini@redhat.com> <20240412104408.GA27645@willie-the-truck> <86jzl2sovz.wl-maz@kernel.org> <86h6g5si0m.wl-maz@kernel.org> <20240418141932.GA1855@willie-the-truck> <20240419112432.GB2972@willie-the-truck> Message-ID: Subject: Re: [PATCH 1/4] KVM: delete .change_pte MMU notifier callback From: Sean Christopherson To: Will Deacon Cc: Marc Zyngier , Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Oliver Upton , Tianrui Zhao , Bibo Mao , Thomas Bogendoerfer , Nicholas Piggin , Anup Patel , Atish Patra , Andrew Morton , David Hildenbrand , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Fri, Apr 19, 2024, Will Deacon wrote: > > @@ -663,10 +669,22 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm, > > break; > > } > > r.ret |= range->handler(kvm, &gfn_range); > > + > > + /* > > + * Use a precise gfn-based TLB flush when possible, as > > + * most mmu_notifier events affect a small-ish range. > > + * Fall back to a full TLB flush if the gfn-based flush > > + * fails, and don't bother trying the gfn-based flush > > + * if a full flush is already pending. > > + */ > > + if (range->flush_on_ret && !need_flush && r.ret && > > + kvm_arch_flush_remote_tlbs_range(kvm, gfn_range.start, > > + gfn_range.end - gfn_range.start + 1)) > > What's that '+ 1' needed for here? (a) To see if you're paying attention. (b) Because more is always better. (c) Because math is hard. (d) Because I haven't tested this. (e) Both (c) and (d).